Prior art of possible revealing includes the following U.S. Letters Pat. No. 4,324,290 issued Apr. 13, 1982 to Moranne; U.S. Pat. No. 4,331,321 issued May 25, 1982 to hesse; U.S. Pat. No. 4,448,321 issued May 15, 1984 to Hanlet; and U.S. Pat. No. 4,651,815 issued Mar. 24, 1987 to Logic et al.
Efforts of the automotive industry to boost the horsepower and efficiency while reducing the gas emissions and vehicle weight have also caused higher operating temperatures. Because, of these new higher temperatures levels, the loss of coolant liquids can quickly result in major engine damage. Heat exchangers, more commonly termed radiators, are used conduct the heat away from the liquid coolant. While core construction employing metals continue to be used because of their thermal conductivity over other materials the header tank construction has given way to become a one piece plastic part.
Most typically, these tanks were brazed or soldered to the core header plates which define the ends of the core pile tubes. Because of the properties of plastic, bonding or fusing technology can no longer be employed. In lieu therefore, to effect the necessary seal, a gasket is disposed between the tank and the header plate. Any of a variety of mechanical means are employed to hold the components in assembled relation while the gasket is in compression, to assure a seal, at the operating pressure for which the heat exchanger was designed.
All previous connections make use of the core metals as a spring clamp, however, all of these materials have poor spring qualities and major deforming should be avoided except when in the dead soft condition. Cracking or breaking is likely when in the annealed condition if more than a slight deflection. An assembled radiator could not be annealed because the high temperature required are much higher than plastics can withstand.
Some prior art connections require drastic bending of the header tank to provide clearance for either a flange or lug to disconnect the tank whereby recantation is impractical. It is also noted that these connection are, likewise, held by bending stresses. Another prior art connection shows hooked lugs formed on the tank wall poking thru apertures. This arrangement, as with the flange is a highly stressed area and the applied forces are cantilevered from the wall. There are no plastic tank type automotive radiator parts available; only complete radiators ar sold to replace a leaking or otherwise damaged radiator. The failed radiator has little scrap value because of the labor required salvage the metal core from the plastic tank.
It is, of course, necessary that the means employed to effect the connection be strong and long lived to prevent leakage. At the same time, it is desirable that the means be such that assembly of the component parts can be effected for servicing. It is also desirable that the means utilized lend themselves to use in mass production to minimize cost.